I have search the HOWTOs on xinetd and inetd, all of which left me confused. I even tried some instructions from Redhat, but the config files these guides reference are seemingly nonexistent with gentoo.

In order to telnet into a gentoo box, you will need to install a telnetd since one isn't installed by default. You can emerge net-misc/netkit-telnetd, and sys-apps/xinetd. At that point, you can add this to your /etc/xinetd.conf: